Oil consumption can occur in an internal combustion engine in multiple ways. Oil consumption can occur when oil from the crankcase migrates past the piston rings into the combustion chamber and is consequently burned off during combustion of the air/fuel mixture. The byproducts of combustion, including the burned oil, are mostly carried away from the engine with the exhaust. Oil consumption can also occur as oil mist is carried away with engine blowby flows (e.g., when pressure within the crankcase is released by ventilation of crankcase gases).
One way of measuring oil consumption for an internal combustion engine may include using what is known as an “oil scale cart.” An oil scale cart includes a reserve oil tank separate from the engine. The oil scale cart may be configured to pump oil from the reserve tank into the engine during the course of an engine bench test. Pumping oil into the engine in this manner can maintain a predetermined amount of oil in the engine despite oil being consumed during operation of the engine. The oil scale cart may include a device for measuring the weight of the reserve tank (e.g., a force transducer, a.k.a. “load cell”). As the oil is pumped out of the reserve tank, the scale measures the reduction in the weight of the reserve tank. Because the oil pumped out of the reserve tank replenishes the oil consumed by the engine, the weight loss of the reserve tank, ideally, may be equivalent to the oil weight lost by the engine.
In practice, it can be difficult to determine whether an oil scale cart is working properly. Although the load cell may be calibrated, the combination of a running engine with an operating oil scale cart is a dynamic system. Such a dynamic system may have variables that can influence the accuracy of the load cell measurement. These variables may include oil temperature, pressure in the engine crankcase, pressure in the reserve tank, the agitation of the oil, flow rate between the engine and the reserve tank, and the rate of oil consumption.
Systems have been developed to verify the measurements made by oil-scale-cart-type oil consumption measuring devices. For example, U.S. Pat. No. 5,273,134, issued on Dec. 28, 1993, to Hegemier et al. (“the '134 patent”), discloses an oil consumption measuring device having two separate measuring systems. The '134 patent includes both a load cell and a metering pump to determine the amount of oil pumped from a reservoir into the engine to compensate for oil consumption.
While the '134 patent may provide a system for verifying the accuracy of the oil consumption measurement, this verification system has shortcomings of its own. For example, the verification system of the '134 patent does not account for certain variables that have been shown to have an effect on the accuracy of oil consumption measurements, such as, for example, oil temperature, oil pressure, oil agitation, oil transfer flow rates (e.g., between the reservoir and the engine), and the actual rate of oil consumption. In addition, the system of the '134 patent provides no engine lubrication system simulating functions to facilitate determination of the effects that these variables may have on the accuracy of oil consumption measurements. Further, the '134 patent provides no troubleshooting or calibrating capability for diagnosing and/or compensating for possible inaccuracies with its own measuring systems. Also, the '134 patent requires additional equipment, such as a separate reservoir used to determine the level of engine oil in the engine being tested. This reservoir may need to be positioned at a particular height with respect to the engine in order for an accurate oil level to be determined, thus adding complexity to the system and its use.
The disclosed engine lubrication system simulating device is directed toward overcoming one or more of the problems set forth above.